docs: def deskew(S):
      """Converts a skew-symmetric cross-product matrix to its corresponding
      vector. Only works for 3x3 matrices.
  
      Parameters
      ----------
      S : :obj:`numpy.ndarray` of float
          A 3x3 skew-symmetric matrix.
  
      Returns
      -------
      :obj:`numpy.ndarray` of float
          A 3-entry vector that corresponds to the given cross product matrix.
      """
      x = np.zeros(3)
      x[0] = S[2,1]
      x[1] = S[0,2]
      x[2] = S[1,0]
      return x